12.1 List three design goals for a firewall. 12.2 List four techniques used by firewalls to control access and enforce a security policy. 12.3 What information is used by a typical packet filtering firewall? 12.4 What are some weaknesses of a packet filtering firewall? 12.5 What is the difference between a packet filtering firewall and a stateful inspection firewall? 12.6 What is an application-level gateway? 12.7 What is a circuit-level gateway? 12.9 What are the common characteristics of a bastion host? 12.10 Why is it useful to have host-based firewalls? 12.11 What is a DMZ network and what types of systems would you expect to find on such networks? 12.12 What is the difference between an internal and an external firewall?